Mailsmith 2.3.1 and later from Stickshift Software. (By applying
this workaround
you can use SpamSieve with Mailsmith 2.1.5.)

Outlook from Microsoft Office
2011 (14.x) and later, including Outlook 2016 (15.x and 16.x) from Office 365
(limitations described in the Setting Up Outlook 2016 section).
Outlook Live and other browser-based mail are not supported, except via
the Mac clients listed here.

Postbox 2.0 and later from Postbox, Inc.
Postbox Express and the (discontinued) Mac App Store version of Postbox
are not compatible.

PowerMail 4.0 and later (6.x recommended) from CTM Development.
PowerMail only supports SpamSieve with POP accounts.

iOS Mail and Web Mail

SpamSieve does not run on iOS, but you can use it together with your Mac to
filter mail on your iPhone, iPad, or iPod touch. This is described in the
iPhone Spam Filtering section.

Entourage v.X (2001) and later (Entourage 2004 or 2008
recommended) from Microsoft.

Eudora 5.x or 6.x (in Sponsored or Paid mode) from
Qualcomm. SpamSieve will also work with Eudora 8.0.0b1
(a.k.a. Penelope) if you follow the Thunderbird instructions.
It does not work with Eudora 8.0.0b2 or later.

MailForge 2.0.4 and later from Macsimize
Software (formerly from Infinity Data Systems).

SpamSieve filters all of your mail accounts. There is no extra charge for
additional addresses.

Multiple Mail Programs

You can freely switch between mail programs or even use multiple mail programs
at once. SpamSieve will share its training data and statistics among them.

Unsupported Mac Mail Programs

SpamSieve is not currently compatible with the following mail programs. You can,
however, use Apple Mail in the background to run SpamSieve but use these
programs to read your mail and to train SpamSieve (via the drone setup’s
special training mailboxes).

Canary Mail is not sufficiently extensible for
us to connect it with SpamSieve. We have offered to help the
developers add support for SpamSieve, and they have expressed interest.
Sending them feedback
will help them prioritize this feature.

Mailbox is not sufficiently extensible
for us to connect it with SpamSieve. This is not likely to change because
the product has been discontinued.

MailPlane is not sufficiently extensible
for us to connect it with SpamSieve. Please contact the developers and tell them that
you would like to use SpamSieve with it.

Mail Pilot is not sufficiently extensible
for us to connect it with SpamSieve. We have offered to help the Mail
Pilot developers add support for SpamSieve. Sending them feedback will
help them prioritize this feature.

Newton is not sufficiently extensible
for us to connect it with SpamSieve. Please contact the developers and tell them that you would
like to use SpamSieve with it.

Spark is not sufficiently extensible for
us to connect it with SpamSieve. We have offered to help the Spark
developers add support for SpamSieve, and they have expressed interest.
Sending them feedback will help them
prioritize this feature.

Sparrow is not sufficiently extensible
for us to connect it with SpamSieve. The Sparrow developers were
interested in adding support for SpamSieve, but the product has since
been acquired by Google and seems to no longer be under development.

Thunderbird 3.0 and
later. Due to changes in Thunderbird, it does not look like it will be
possible to create a SpamSieve plug-in for newer versions of Thunderbird.
However, SpamSieve does work with Postbox, which is an enhanced version of
Thunderbird.

Unibox is not sufficiently extensible for
us to connect it with SpamSieve. We have offered to help the Unibox
developers add support for SpamSieve. Sending them feedback will help
them prioritize this feature.

Mail Program Differences

SpamSieve works roughly the same way with each mail program. This section
describes features that are only available in certain mail programs.

These mail programs allow for more accurate filtering because they let SpamSieve
access the entire raw source of each message, including the attachments: Apple
Mail, Airmail, Entourage, GyazMail, MailMate, Mailsmith, Outlook, Outlook
Express.

Custom Rules

These mail programs let you control SpamSieve through a regular rule, so that
you can determine how it interacts with your other rules: Apple Mail, Entourage,
GyazMail, MailMate, Mailsmith, Outlook 2011, PowerMail.